Using underwater balloons to store energy

By Jenny Tan

November 26, 2015

In the depths of Lake Ontario, giant underwater balloons are set to store some of Toronto’s excess energy.

Toronto-based Hydrostor activated what it claims is the world’s first underwater compressed air energy storage system last week. The system uses compressed air to store energy generated during non-peak periods.

With a capacity of 660 kilowatt hours, the underwater balloons can store enough energy to power 330 homes.

During non-peak periods, excess electricity is passed through an air compressor. The compressed air is then sent through a pipeline from the facility on Toronto Island to the underwater balloons in Lake Ontario. When energy is needed, the process is reversed. The weight of the water pushes the compressed air back up the pipeline, where an expander converts it back to electricity that can be fed back into Toronto’s electrical grid.

Toronto Hydro will operate the facility.

“The G20 is talking about getting off fossil fuel by 2050,” Hydrostor CEO Curtis VanWalleghem told Canadian Manufacturing. “To do that, our electricity system has to incorporate storage so we don’t need as much backup diesel and natural gas capacity — that’s what this can do.”

The underwater balloon system produces zero emissions and conserves heat from the compression process to be reused.

Commercially viable energy storage technology is a key to establishing mainstream renewable energy. The amount of energy renewable sources produce often varies depending on weather conditions, which creates a need for reliable storage. But some storage options can only be used in particular locations, including pumped hydro, which involves pumping water from low to high elevations to be released when energy is needed. The underwater balloons are meant to be more easily scalable for projects of different sizes.

The interest in energy storage has increased in recent years. In May, Silicon Valley innovator Elon Musk announced the Powerwall, a rechargeable lithium-ion battery for residential homes. The commercial version, the Powerpack, is also available for utility companies. A large Californian utility also recently decided to build a battery plant over a natural gas power plant.

Ontario leads Canada in energy storage initiatives. In July last year, the province announced 34 megawatts of energy storage projects with technologies from flywheels to thermal energy storage. In August 2014, Oshawa Power installed thirty rooftop solar panel and battery storage units. And other provinces are taking note. Alberta Innovatesfunded six energy storage projects in the province this year.

Hydrostor hopes to sell its system to coastal cities and island nations making the switch to renewable energy.